1. Field of the Invention
The present invention relates to digital circuits. More specifically, the present invention relates to systems and methods for multiplexing a plurality of communication resource interfaces.
2. Description of the Related Art
Modern electronic devices continue to evolve into ever-higher levels of integration. While devices used to implement a given electronic function were once wired together from discrete components, now, highly integrated ‘chips’ are produced to consolidate the discrete components and functions into a single package. This lowers cost, reduces size and makes more reliable product manufactured in this manner. Examples of such highly integrated devices include wireless telephones, personal digital assistants, radio transceivers, media recorders and players, device controllers and all kinds of other devices and functions.
Today, designers of integrated systems that combine more than one of these integrated devices into a single product are faced with the task of integrating integrated devices. For example, if a designer wishes to integrate a wireless telephone and a personal digital assistant, they must design a circuit for accomplishing such integration or create an entirely new integrated device which incorporates all the components and functions desired for the integrated product. The latter approach may be an expensive and risky investment in an emerging market.
Aside from sharing power supply and ground circuits, highly integrated devices must communicate in some fashion because there is usually a software application dedicated to each integrated device. To yield a gracefully functioning integrated product, it is necessary to integrate both the hardware and the software. This usually implies a parallel or serial communications port interconnecting the two integrated devices. This can be straight forward in the case where two devices are integrated into a product. Serial communications protocols and physical interfaces are often times preferred because a smaller quantity of printed circuit board area is required to route the relatively fewer circuit traces. However, where there are more than two devices integrated into a product, the connection of a plurality of interfaces are more problematic.
Where three or more integrated devices are integrated into a product, the designer must design a communications interface, or multiplexing circuit that not only interconnects the various devices, but also deals with issues of contention between the devices that inevitably arise. Of course, the design of such circuitry is within the ability of many designers, given there are not great limitations placed on cost, development time, and printed circuit board area required. However, this is rarely the case. In modern, highly integrated, devices that compete in open markets, there is always a great pressure to hold size and cost down, while at the same time providing short product development cycles and good reliability.
Thus there is a need in the art for a low cost device for interconnecting and multiplexing three or more interfaces among devices.